Transporting crystals in the form of slurries is often a convenient method of transporting various materials to places where they are needed in various commercial operations. One example is the transportation of reactants such as potassium benzoate (KBz) used in the preparation of terephthalic acid (TPA). TPA is important in the production of polyester fibers.
For such transporting, it is important that the slurries have low viscosities. Low viscosity slurries, in general, (as compared with high viscosity slurries) are more easily pumped through transfer tubes, exhibit less deposition of crystals and decomposed material on the walls of the transfer tubes, and do not require such high transfer tube temperatures. Therefore, for these reasons, low viscosity slurries are preferable.
The prior art has taught that average particle size and particle shape are factors which affect viscosity. It is also known that for a given material having a given particle shape, as the size of the average particle decreases, the viscosity of the slurry produced therefrom increases.
However, the prior art has not determined that when the material used to form the particles is held constant, a slurry produced from particles having a plate shape in the slurry will have a higher viscosity than a slurry produced from particles having a granular shape in the slurry. Furthermore, the problem of lowering viscosity in a particular slurry has not been solved for all materials.
Certain materials in the form of thin, plate-shaped individual crystals have been found to form high viscosity slurries. For example, when an aqueous potassium benzoate solution is mixed with hot terphenyl, a high viscosity slurry is formed which contains thin, plate-shaped individual crystals which range in size from about 10 to about 2000 .mu.m in diameter, the majority lying within the range from about 200 to about 1100 .mu.m.
It is an object of this invention to make a low viscosity slurry of crystals in a suitable dispersant.
It is also an object of this invention to transport potassium benzoate crystals which are used in a step in the production of valuable terephthalic acid.